Mexican authorities arrested a former U.S. university professor on Tuesday (June 18), who recently was added to the FBI's 10 most-wanted list and faces sex crimes charges in the Philippines.

Sixty-four year-old Walter Lee Williams was arrested in the southern beach resort of Playa del Carmen. The FBI said he was an anthropology and gender studies professor at the University of Southern California until 2011.

According to the FBI, under the guise of academic research, Williams is believed to have traveled in the Philippines and elsewhere in Southeast Asia to have sex with underage boys.

The bureau said it had identified 10 victims between ages 9 and 17.

Police reportedly found Williams at a cafe on Tuesday night in the popular resort of Playa Del Carmen, a short drive from Cancun, which is a popular U.S. vacation destination.

The FBI added Williams to the 10 most-wanted list on Monday. The bureau was offering a $100,000 reward for information leading directly to his arrest.

The bureau uses the most-wanted list, which has been in place since 1950, to draw attention to some of the most dangerous U.S. fugitives. Over the years 469 fugitives on the list have been caught or located.